1. Field of the Related Art
The invention relates to an anastomosis system and method for controlling a tissue site in an anastomosis procedure wherein blood vessels or other tubular or hollow organs are joined together by tissue bonding.
2. Background of the Related Art
Vascular anastomosis is a procedure by which two blood vessels within a patient are surgically joined together. Vascular anastomosis is performed during treatment of a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. In coronary artery disease (CAD) an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. Treatment of CAD involves the grafting of a vessel in the form of a prosthesis or harvested artery or vein to reroute blood flow around the occlusion and restore adequate blood flow to the heart muscle. This treatment is known as coronary artery bypass grafting (CABG).
In the conventional CABG, a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, a heart lung machine is used to circulate the patient""s blood so that the heart can be stopped and the anastomosis can be performed. In order to minimize the trauma to the patient induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patients chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or stopped heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG procedures, the surgeon has to suture one end of the graft vessel to the coronary artery and the other end of the graft vessel to a blood supplying vein or artery, such as the aorta. The suturing process is a time consuming and difficult procedure requiring a high level of surgical skill. In order to perform the suturing of the graft to a target vessel such as the coronary artery or the blood supplying artery the surgeon generally has an assistant hold the edges of the incision in the target vessel while the surgeon takes small stitches as close as possible to the edges of the incision. This suturing requires a high degree of precision and is quite time consuming. In addition, during conventional CABG procedures blood flow at the anastomosis site is stopped during suturing. This prevents bleeding from the incision site but also prevents blood from reaching a portion of the heart muscle served by the vessel.
Various alternatives to suturing are known for performing anastomosis. These techniques generally involve securing the tissue with mechanical fasteners such as staples or fittings which compress the tissue surfaces together. Sutureless techniques for performing anastomosis are disclosed in U.S. Pat. Nos. 3,254,650; 3,774,615; 4,350,160; 4,352,358; 4,368,736; 4,523,592; 4,553,542; 4,593,693; 4,607,637; 4,624,255; 4,624,257; 4,657,019; 4,747,407; 4,907,591; 4,917,087; 4,917,090; 4,917,091; 5,119,983; 5,234,447; 5,336,233; 5,366,462; 5,456,714; 5,571,167; 5,669,918; 5,676,670; 5,695,504; 5,702,412; 5,707,380; 5,725,544; 5,797,920; 5,817,113; and 5,904,697.
While offering certain advantages over suturing, mechanical fastening techniques such as stapling still have disadvantages. Staples, for example, can produce high mechanical loads which may result in tearing of the tissue around the staples. As a result, staples cannot be placed too close to the incision cite in the target vessel.
Another alternative to suturing in general surgical procedures is tissue bonding. Tissue bonding methods include adhesive bonding and tissue welding. Adhesive bonding generally involves applying a tissue adhesive to either or both of the tissue mating surfaces and applying clamping pressure until the adhesive sets. Tissue welding is generally accomplished by heating the tissue through energy dissipation in the affected tissue. The energy applied to the tissue can be in the form of electrical power (usually RF power), light energy (e.g., laser) or ultrasonic energy. During welding, the heated tissue in the weld region undergoes cellular dehydration and denaturation of proteins which results in formation of the weld. Tissue bonding procedures are disclosed in U.S. Pat. Nos. 4,892,098 5,156,613; 5,290,278; 5,300,065; 5,364,389; 5,540,677; 5,611,794; 5,669,934; 5,707,369; 5,749,895; 5,824,015; 5,827,265; and 6,004,335.
Tissue bonding techniques, however, have met with limited success when used for performing vascular anastomosis. With tissue welding, achieving a strong bond requires not only precise control of energy delivery to the tissue in the weld region but also proper tissue apposition. Energy delivery is important to ensure that the desired amount of energy is absorbed by the tissue. Tissue apposition is important because the sections of tissue to be welded together must be in substantial abutment and accurate alignment to ensure that the energy applied to the tissue effectively fuses the tissue in the weld area. Deficient apposition can cause leakage or the formation of weak bonds. Tissue apposition is also important for adhesive bonding where the tissue mating surfaces must be held in proper position until the adhesive sets. Proper tissue apposition during vascular anastomosis is particularly difficult to achieve due to the small size and the flexible, circular configuration of the blood vessels involved.
Accordingly, there exists a need to provide a device for performing vascular anastomosis by tissue bonding. There also exists a need for a device which provides precise apposition of the graft and target vessels for tissue bonding during in an end-to-side anastomosis procedure.
The present invention relates to a system and method for performing vascular anastomosis by tissue bonding techniques. The present invention also relates to a method of controlling a tissue site during an anastomosis procedure wherein a graft vessel and a target vessel are attached together using a tissue bonding technique. Suitable tissue bonding techniques include adhesive bonding and tissue welding. The anastomosis system and method of the present invention may be used on a pressurized or unpressurized target vessel.
In accordance with one aspect of the present invention, a method of performing anastomosis is provided. The method employs an anastomosis system including an elongated anvil having tissue contacting surfaces and a graft vessel fixture movable with respect to the anvil. The graft vessel fixture further includes clamping members each having one or more clamping surfaces adapted to compress the tissue on opposite sides of the graft vessel against the anvil. The method involves steps of: inserting the elongated anvil through the wall of a target blood vessel and positioning the elongated anvil along an interior of the target blood vessel wall; positioning a graft vessel adjacent an exterior of the target blood vessel wall; moving the fixture toward the anvil to clamp the graft and target vessel tissue between the tissue contacting surfaces of the anvil and the clamping surfaces of the fixture; and applying energy to the tissue clamped between the electrode surfaces on the anvil and the clamping surfaces of the fixture to secure the graft and target vessels together. In a preferred embodiment of the present invention, the method also comprises steps of making an opening in the target vessel to allow blood to flow between the target vessel and the graft vessel and removing the anvil.
In accordance with another aspect of the present invention, an anastomosis system is provided for connecting a graft vessel to a target vessel by the application of energy. The anastomosis system includes an elongated anvil having tissue contacting surfaces and a graft vessel fixture. The fixture includes clamping members each of which has one or more clamping surfaces adapted to compress the graft and target vessel tissue on opposite sides of the graft vessel against the anvil. The fixture is movable relative to the anvil so as to allow the graft and target vessel tissue to be clamped between the anvil and the fixture at the anastomosis site. Furthermore, the tissue contacting surfaces of the anvil and/or the clamping surfaces of the fixture are provided with one or more energy applying surfaces.
In accordance with another aspect of the present invention, an anvil for use in performing anastomosis between a graft vessel and a target vessel is provided. The anvil includes a handle and an elongated anvil arm extending from the handle. The anvil arm has at least one energy applying surface on an upper tissue contacting surface thereof.
In accordance with another aspect of the present invention, a method of performing an anastomosis between a target vessel and the end of a graft vessel is provided. The method includes steps of: applying a tissue adhesive to mating surfaces of the graft vessel and/or target vessel; inserting an elongated anvil through the wall of the target vessel and positioning the anvil along an interior of the target vessel wall; positioning the end of the graft vessel adjacent an exterior of the target vessel wall; and curing the adhesive.
In accordance with a further aspect of the present invention, an anastomosis system for connecting a graft vessel to a target vessel using a tissue adhesive is disclosed. The anastomosis system includes an elongated anvil having tissue contacting surfaces thereon and a graft vessel fixture including clamping members each having one or more clamping surfaces adapted to compress the graft and target vessel tissue on opposite sides of the graft vessel against the tissue contacting surfaces of the anvil. The fixture is movable relative to the anvil so as to allow the graft and target vessel tissue to be clamped between the anvil and the fixture at the anastomosis site. The anvil and/or the graft vessel fixture are provided with one or more tissue adhesive applicators adapted to supply a tissue adhesive to mating surfaces of the graft and/or target vessel.